Azeotropic mixture for use as a refrigerant



Patented June 20, 1950 L AZEOTROPIC MIXTURE FOR USE AS A REFRIGERANTWinston Harrison Reed, Syracuse, N. Y., assignor to Carrier Corporation,Syracuse, N. Y., a corporation of Delaware No Drawing. ApplicationAugust 30, 1946, Serial No. 694,145

3 Claims. 1

This invention relates to refrigerant mixtures and to a method of usingthe same.

The chief object of my invention is to provide a refrigerant mixturecomposed of two or more refrigerants capable of forming an azeotropicmixture, which boils at a constant temperature as if it were composed ofa single substance.

I have found a mixture of monochlorodifiuoromethane and propane to beparticularly advantageous. Monoohlorodifluoromethane possesses a boilingpoint of -41.4 F. at atmospheric pressure while propane possesses aboiling point of --48.1 F. at atmospheric pressure (14.69 pounds persquare inch). Monochlorodifluoromethane at a temperature of 32 F.provides a pressure of about 73 pounds per square inch absolute. Propaneat a temperature of 32 F. possesses a pressure of about '75 pounds persquare inch absolute. According to Raoults law, any mixture of suchmaterials should possess a pressure between 20 the two extremes.Contrary to this law, however, the addition of propane tomonochlorodifluoromethane increases the pressure over a wide range toprovide a highly desirable increase in capacity of a refrigerationsystem designed for While I have described a preferred embodiconsistingin introducing into a refrigeration use with monochlorodifluoromethane.Such increase in capacity amounts to about 18% depending upon thequantity of propane mixed with monochlorodifluoromethane.

The azeotropic mixture is formed having a constant boiling point of 32F. at an absolute pressure of approximately 86.2 pounds per square inchwhen monochlorodifluoromethane and propane are mixed in the proportionsof approximately 68 parts to 32 parts by weight. The azeotropic mixtureso formed possesses a lower boiling point than eithermonochlorodlfluoromethane or propane. The azeotropic mixture is stable,non-corrosive in the system and is lower in cost thanmonochlorodifiuoromethane.

The azeotropic mixture of my invention may be employed in equipmentdesigned for use at a condensing temperature of about 105 F. and at anevaporating temperature of about 40 F. In operation the azeotropicmixture may be condensed at a condensing temperature of about 105 F.,then transferred to the evaporator or heat exchanger and evaporated ata. temperature of about 40 F. to provide the required heat transfer.

It will be appreciated that the respective amounts of propane andmonochlorodifluoromethane in the azeotrope vary in accordance withtemperature and pressure; that is, the amount of propane contained inthe azeotrope varies slightly as the temperature, for example,increases.

system of a refrigerant consisting of monochlorodifluoromethane having aboiling point of -41.4 F. at atmospheric pressure and propane having aboiling point of about -48.1 F. at atmospheric pressure, the refrigeranthaving a boiling point of 32 F. at about 86.2 p.s.i.a., evaporating therefrigerant, the concentration of the refrigerant remainin the same asit is vaporized with each of the components remaining in the same ratiowith respect to the other, and then successively compressing and condensing the refrigerant, the components in the refrigerant remaining in thesame ratio during the compression and condensation stages.

2. A refrigerant for use in a compressorcondenser-expander refrigerationsystem consisting of a mixture of monochlorodifluoromethane and propanehaving a pressure at a predetermined temperature greater than thepressure of either component at such temperature, said mixture at itsboiling temperature containing the same proportions of the components inboth liquid and vapor phases.

3. A refrigerant for use in a compressor-condenser-expanderrefrigeration system consisting of an azeotropic mixture ofmonochlorodifluoromethane and propane and containing approximately 32%by weight of propane, said mixture having a boiling point of 32 F. at anabsolute pressure of about 86.2 pounds per square inch, said mixture atits boiling temperature containing the same proportions of thecomponents in both liquid and vapor phases.

' WINSTON HARRISON REED.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

1. A METHOD OF PRODUCING REFRIGERATION EFFECT CONSISTING IN INTRODUCINGINTO A REFRIGERATION SYSTEM OF REFRIGERANT CONSISTING OFMONOCHLORODIFLUOROMETHANE HAVING A BOILING POINT OF -41.4*F. ATATMOSPHERIC PRESSURE AND PROPANE HAVING A BOILING POINT OF ABOUT -48.1*FAT ATMOSPHERIC PRESSURE, THE REFRIGERANT HAVING A BOILING POINT OF 32*F.AT ABOUT 86.2 P.S.I.A., EVAPORATING THE REFRIGERANT, THE CONCENTRATIONOF THE REFRIGERANT REMAINING THE SAME AS IT IS VAPORIZED WITH EACH OFTHE COMPONENTS REMAINING IN THE SAME RATIO WITH RESPECT TO THE OTHER,AND THEN SUCCESSIVELY COMPRESSING AND CONDENSING THE REFRIGERANT, THECOMPONENTS IN THE REFRIGERANT REMAINING IN THE SAME RATIO DURING THECOMPRESSION AND CONDENSATION STAGES.